Apparatus for forming metallic casing liner



Aug. 31, 1965 R. P. VINCENT 3,203,483

APPARATUS FOR FORMING METALLIC CASING LINER 8 Sheets-Sheet 1 OriginalFiled Aug. 9, 1962 AAA/ e FIG.

INVENTOR. RENIC P. VINCENT MKM ATTORNEY Aug. 31, 1965 R. P. VINCENT3,203,483

APPARATUS FOR FORMING METALLIC CASING LINER 8 Sheets-Sheet 2 OriginalFiled Aug. 9, 1962 INVENTOR. RENIC P. VINCENT /Zud/KM ATTORNEY Aug. 31,1965 R. P. VINCENT 3,203,483

APPARATUS FOR FORMING METALLIC CASING LINER Original Filed Aug. 9, 19628 Sheets-Sheet 3 INVENTOR. RENIC P. VINCENT ATTORNEY 1965 R. P. VINCENT3,203,483 APPARATUS FOR FORMING METALLIC CASING LINER Original FiledAug. 9, 1962 8 Sheets-Sheet 4 I /i so I;

1. mlllmim Wa l;

FIG. 6 INVENTOR.

RENIC P. VINCENT KMKM Y ATTORNEY Aug. 31, 1965 R. P. VINCENT 3,203,433

APPARATUS FOR FORMING METALLIC CASING LINER Original Filed Aug. 9, 1962'8 Sheets-Sheet 5 T no m J H 1 H5 H5 r '1 n2 I MoTbA B! U f I36 [m naeINVENTOR. RENIC P. VINCENT BY KM ZXM FIG. 7 ATTORNEY 8- 1, 1965 R. P.VINCENT 3,203,483

APPARATUS FOR FORMING METALLIC CASING LINER Original Filed Aug. 9, 19628 Sheets-Sheet 6 /-"'IIO I62 \IGI REDUCTION GEAR 38 MOTOR -|5e MOTORREDUCTION GEAR FIG. 10

INVENTOR. -|22 RENIC avmczm KMKM FIG. 9

ATTORNEY Aug. 31, 1965 R. P. VINCENT APPARATUS FOR FORMING METALLICCASING LINER 8 Sheets-Sheet '7 Original Filed Aug. 9, 1962 FIG.

INVENTOR. RENIC P. VINCENT BY fiiwagm FIG. ll

ATTORNEY Aug. 31, 1965 R. P. VINCENT 3,

APPARATUS FOR FORMING METALLIC CASING LINER Original Filed Aug. 9, 19628 Sheets-Sheet 8 INVENTOR. RENIC P. VINCENT M ZM ATTORNEY United StatesPatent 9 Claims. (Cl. 166-207) This invention relates to apparatus forsetting a metallic liner inside casing in a well. More particularly, itrelates to apparatus for performing such an operation in which a goodseal is formed and maintained between the casing and liner. This is adivision of my US. patent application 216,949 filed August 9, 1962,which is in turn a continuation-in-part of my US. patent applicationSerial Number 123,039, filed July 10, 1961.

A principal use for liners in wells is to avoid the necessity forrunning an entire string of smaller casing in a Well which already has alarger string of casing. Possibly the most common use is in the bottomof the well where the existing casing does not extend to the bottom ofthe well. In this use, a short liner is lowered through the casing intothe bottom of the well where a seal is formed between the liner andcasing to provide a metallic liner in the well to substantially its fulldepth. In such cases a seal between the liner and casing is generallyprovided by Portland cement pumped in back of the liner to fill thespace between the liner and casing. Such seals are seldom perfect. As aresult, if the pressure of fluids from the formations penetrated by thewell is applied to the outside of the liner and casing, a leak usuallyresults.

The liner is rarely as thick or strong as the casing. When pressure isapplied outside the liner and easing, the liner is compressed more thanthe casing and a crack forms between them even if none existed before.As soon as an opening is formed for entrance of fluids between thecasing and liner, the pressures inside and outside the casing tend tobecome balanced, permitting the casing to return to its unstressedcondition. This further widens the opening between the casing and liner.Since the wider the opening, the more the casing stress is relieved andsince the more this stress is relieved, the wider the opening becomes,it is apparent that a leak between the casing and liner can hardly beavoided even though a long overlap of casing and liner is provided.

This problem is particularly acute if it is desired to place a steelliner or patching steel sleeve over parted casing or a split or hole incasing. In this case, it is difficult to place Portland cement betweenthe casing and liner and hold the cement in place until it sets. Inaddition, the application of pressure outside the liner quickly causesleakage in the manner just described.

With these problems in mind, an object of this invention is to provideapparatus for setting a metallic liner inside well casing or othercylindrical metallic vessels, so that a seal is established andmaintained between the liner and casing even when pressure is appliedoutside the liner, as through a hole in the casing. Other objects willbe apparent to those skilled in the art from the following drawing,description and claims.

In general, I accomplish the objects of my invention by using a.vertically corrugated metal liner. The external cross-sectionalperimeter of this corrugated liner is greater than the internalcross-sectional circumference of the casing, but the maximum externalcross-sectional dimension of the corrugated liner is less than theinternal diameter of the casing so the liner can be inserted into thecasing. A mat of glass fibers, preferably woven glass cloth, is placedaround the corrugated liner and this mat is saturated with a settableliquid resin, such as epoxy resin, before the liner is placed inside thecasing. After the liner is placed at the desired location in the casing,an expanding tool is run through the corrugated liner to cause it toassume a cylindrical shape inside the casing. The liner is thus left insubstantially maximum compressive stress, which is an essential aspectof my method.

In the drawing,

FIGURE 1 is a view in cross-section of a preferred form of the apparatusfor setting a liner in casing;

FIGURE 2 is an isometric view, partly in section, to show the form ofthe corrugated liner and the preferred form of head for expanding theliner;

FIGURE 3 is another view in section of a portion of the apparatus ofFIGURE 1 in the process of expanding a corrugated liner against theinside surface of a casing;

FIGURE 4 shows a portion of a section of FIGURE 3 along line 44;

FIGURE 5 shows a portion of a section of FIGURE 3 along line 5-5;

FIGURE 6 is a view in cross-section of another form of apparatus capableof expanding a corrugated liner into contact with the inside surface ofa casing;

FIGURE 7 is a view partly in cross-section of the upper portion ofapparatus in which an electric motor drives a pump to operate the linerexpanding apparatus;

FIGURE 8 is a view in cross-section of the lower part of apparatus, thetop of which is shown in FIGURE 7;

FIGURE 9 is a view partly in cross-section of the upper part of anapparatus employing jack screws driven by motors to set slips and expandthe liner into contact with the casing;

FIGURE 10 is a cross-sectional view of the lower part of the apparatus,the top part of which is shown in FIG- URE 9;

FIGURE 11 is a view in cross-section of the upper portion of anapparatus which can be lowered on an uninsulated wire line to thedesired level in a well, the liner then being set by hydraulic pressureapplied through the casing;

FIGURE 12 is a view in cross-section of the lower part of the apparatusof FIGURE 11;

FIGURE 13 shows apparatus employing multiple pistons in tandem to obtaina greater force with low hydraulic pressures.

In FIGURE 1, the corrugated liner tube 11 is mounted between connector12 and an expanding cone 13. The connector 12 includes a top collarportion 14 which is internally threaded to receive standard well tubing15 which serves to lower the entire liner setting assembly into theWell. Other hollow conduit, such as drill pipe can, of course, be used,if desired. The main body portion of connector 12 includes a centralpassage 16, the upper portion of which is threaded to receive and holdthe top of a polished rod 17. A complete seal between the polished rodand connector 12 is assured by use of O-ring 19 in peripheral groove 20around passage 16. In the top of passage 16 a short pipe 22 with loosecap 23 is provided to prevent scale, dirt, and the like from the inside'wall of the tubing from falling into the hydraulic system below.

Polished rod 17 includes a central bore 24 which connects with theinterior of pipe 22. A piston 25 is mounted on the bottom of polishedrod 17. The piston includes an internally threaded cap 26 for attachmentto the externally threaded bottom portion of polished rod 17. The pistonalso includes flange 27 on which resilient cups 28 and 29 are mounted.Above top cup 29, a passage 30 is provided in the piston which isconnected to the inner bore 24 of polished rod 17.

Piston 25 works in a cylinder 32 having a cap 33 through which polishedrod 17 passes. Packing 34 is provided to form a seal between polishedrod 17 and cap 33. Preferably, an O-ring 35 is provided between thecylinder 32 and cap 33 to insure a good seal between these members.Sleeve 36 rests on the top of cap 33 and supports expanding cone 13.Surrounding sleeve 36 is collet head 37 with collet spring arms 38. Thearms have an inner surface which is spaced from sleeve 37 to permitinward movement of the arms. The arms also have slots 39 (FIGURE 2)between them to permit this same action. Near the tops of arms 38 areoutwardly enlarged portions 40 which perform the final forming action toforce the corrugated liner into a substantially cylindrical shape as thecone and collet head are pulled through the corrugated liner tube by thehydraulic piston and cylinder arrangement shown. Arms 40 are normallysprung out farther than shown in FIGURE 1. In this figure, the arms areshown as being restrained by projecting portions 41 which fit into amating recess 42 in expanding cone 13. This permits lowering theassembly more easily through the well to the desired location.

In FIGURE 2, an exterior view, partly in section, is presented to showmore clearly the form of the corrugated liner tube and the spring armsof the collet head.

FIGURE 3 shows a section of the corrugated liner tube as it is beingexpanded inside casing 43. In this case, the tube 11 is shown covered bya sealing layer 44 made up of glass fibers saturated with a liquid resincapable of being set to a hardened state. In FIGURE 3, projections 41are shown withdrawn from recess 42 so the arms have sprung out into thepositions shown. The expanding cone and collet head have been forcedpartway through the liner tube 11, expanding the liner into asubstantially cylindrical form inside the casing with the glass fibersand resin forming a seal between the casing and liner.

In operation, the liner setting tool is assembled at the surface, asshown in FIGURES 1 and 2, and glass cloth saturated with resin iswrapped around the corrugated tube. The assembly is lowered into thewell in this condition to the location at which the liner is to be set.A liquid, such as oil, is then pumped into the tubing. The oil passesthrough the well tubing, pipe 22, polished rod 17, passages 30 and intothe cylinder 32 above piston 25. As the pressure increases, the pressureon cap 33 causes it to rise, carrying sleeve 36 and expanded head 13upwardly with respect to the polished rod. Upward movement of liner tube11 is restrained by connector 12 attached to the top of the polishedrod. Therefore, as expanding cone 13 rises, it expands corrugated linertube 11. At a level near the bottom of cone 13, the liner has beenexpanded to the form shown in FIGURE 4.

As cone 13 passes upwardly through liner tube 11, the bottom of the tubeeventually strikes the enlarged portions 40 of the collet head springarms. When this happens, upward motion of the collet head is restrainedand causes projections 41 to pull out of restraining recess 42. The armsthen spring outwardly, as shown in FIGURE 3. As cap 33 on the hydrauliccylinder continues to rise, the cap comes in contact with the bottom ofcollet head 37, forcing it through liner tube 11. The spring armscomplete the expansion of the liner tube out against the inner surfaceof the casing, as shown in FIGURE 5, except of course, for the sealinglayer of glass fibers and resin between the liner and easing.

When the upward movement of cap 33, collet head 37, and expanding cone13 causes cone 13 to come into contact with connector 12, the upwardmotion must, of course, stop. This is indicated by an increase of pressure required to inject liquid into the tubing. The expanding cone 13and collect head 37 may then be forced the remaining distance throughthe corrugated liner tube by simply lifting on the well tubing. This ispossible because the frictional drag of the expanded portion of theliner against the casing is sufiicient to hold the liner down againstthe upward pull of the cone and collet head. It has been determined, forexample, that the liner will resist a pull 12,000 pounds per inch oflength of inch thick liner set in 5 /2 inch casing. The upward forcerequired to pull the expanding cone and collet head through the inchthick liner in the 5 inch casing varied from about 15,000 to about60,000 pounds, depending upon weight of easing, heavier casing beingsmaller in internal diameter. It will be apparent that after only a fewinches of the liner have been expanded against the casing, connector 12is no longer needed to hold the liner down while the tube is beingexpanded.

An alternative procedure when cone 13 strikes connector 12 is to releasethe pressure on the tubing, raise the well tubing two or three feet,secure it firmly at the surface, and then resume injecting hydraulicfluid into the tubing. Raising the well tubing will lift connector 12two or three feet above the top of the liner. Expanding cone 13 andcollet head 37 can then be forced on through the liner tube by injectinghydraulic fluid through the tubing.

As soon as the cone and collet head have been pulled completely throughthe liner, the tubing and liner setting assembly are removed from thewell. To avoil pulling a wet string, it is possible to include abreak-off relief seal 50 in the well tubing 15 above cap 23. This sealcan be broken off by dropping a go-devil down the tubing. Breaking ofthe seal allows the liquid in the tubing to leak out as the tubing ispulled from the Well.

The apparatus shown in FIGURES 1 and 2 relies upon the action ofhydraulic pressure to force an expanding cone and collet spring headthrough a corrugated liner tube to expand this tube into a substantiallycircular shape inside the casing. This apparatus is preferred because ofits simplicity and ease of manipulation. It will be apparent, however,that other apparatus can be used to expand the corrugated liner tube.Another apparatus is shown in FIGURE 6. In this apparatus the corrugatedliner tube 11 and the expanding cone 13 are the same as in FIGURE 1, butthe remaining equipment is different.

In the apparatus shown in FIGURE 6, the corrugated tube 11 is restrainedagainst upward movement by slips 60 which are mounted to slide on theoutside surface of slips cone 62. A helical spring 61 in a groove in theouter surface of slips 60 holds the slips in a normally retractedposition. On the top of cone 62 is a cylinder 63 having externalthreads. On the bottom of cone 62 is another cylinder or collar 64.

The cone 62 slides upon a hollow conduit 65, which is attached throughcollar 66 to well tubing or drill pipe on which the assembly is loweredinto the well. The bottom portion of conduit 65 carries external grooves67 in which slide keys 68, which are attached to the inner surface ofcollar 64. These keys cause cone 62 to turn with conduit 65. Slips 60are restrained from turning by drag arms 70 which contact the wellcasing. Thus, when the apparatus is in a well and conduit 65 is turned,cone 62 turns with respect to slips 60. This causes the ends of springarms 71 to move in the threads of cylinder 63 to move the slips up ordown on the outer surface of cone 62.

On the bottom of conduit 65 is mounted a thick-walled, hollow body 73.In the walls of this body are mounted radially acting pistons 74 whichoperate in cylinders 75. A sliding seal is provided between the pistonsand cylinder by packing, such as O-ring 76. A stem or rod 77 on piston74 extends through a passage 78 in the outer wall of body 73. The outerend of rod 77 contacts an arm 81, which is pivoted on pin 82, which isattached to body 73 through mounting bracket 83. The bottom of conduit65 is closed by cap 84.

In operation, the apparatus is assembled at the surface, a wrapping ofresin-saturated glass fabric is applied to the corrugated tube, and theassembly is lowered into the well on well tubing to the level at whichthe liner is to be set. The tubing is then rotated to the right. Thiscauses cone 62 to rotate with respect to slips 60, drag arms 70restraining rotation of the slips. The relative rotation of the cone andslips causes the ends of spring arms 71 to move upward in the threads ofcylinder 63 on the top of cone 62, raising slips 60 with respect to cone62. The upward movement of slips 60 with respect to cone 62 results inthe outward movement of the slips until they come in contact with thecasing. Lifting of the tubing now causes the corrugated liner tube 11 topush firmly against the slips and set them more firmly against thecasing wall.

Continued upward pull on the tubing forces the expanding cone 13 intothe liner 11 until arms 81 come in contact with the liner. At or beforethis time hydraulic pressure is applied through the tubing and conduit65 to the pistons 74. The amount of hydraulic pressure can be carefullycontrolled to provide the desired amount of force on arms 81 to insureproper forming of the corrugated liner tube into a cylindrical shapewithout applying a force sufiicient to damage the casing.

The expanding cone 13 and arms 81 can be forced through the liner tubeby continued upward pull on the tubing until expanding cone 13 comes incontact with collar 64 on cone 62. Further upward movement of the tubingand expanding cone 13 then moves slips cone 62 upwardly with respect toslips 68, thus releasing the slips. Thereupon spring 61 collapses theslips and allows them to move upwardly with the rest of the assembly.Corrugated tube 11, at this point, no longer requires the holding actionof the slips. As explained previously, the frictional drag of only a fewinches length of the liner set inside the casing is enough to hold thetube in place while the expanding cone 11 and arms 81 are pulled throughthe top portion of this corrugated liner tube.

As soon as the expanding cone 11 and arms 81 clear the top of the linertube, the assembly can be simple withdrawn from the well. Preferably,break-01f release seal 58 is provided and is broken by dropping ago-devil to permit any liquid to drain from the tubing and thus avoidpulling a wet string. This also avoids any hydraulic head of liquid inthe tubing from acting on pistons 74 to force arms 81 outwardly againstthe casing wall as the assembly is raised up the well.

In FIGURES 7 and 8 armored electric cable 110 supports the apparatusthrough a head, 111 which contains hydraulically actuated slips 112.Each slips member includes a piston portion 113 operating in cylinder114 formed in head 111. O-ring grooves 115 surrounding cylinders 114receive O-rings 116 which form a seal around piston portions 113. Theends of piston portions 113 are exposed to central bore 117 in head 111so that hydraulic pressure can be applied through bore 117 to pistonportions 113 to force the slips outwardly. Central bore 117 alsoreceives conduit 118 through which electrical conductors 119 pass to amotor. To the bottom of head 111 polished rod 128 is attached. Thispolished rod also has a central passage 121 aligned with bore 117 toreceive conduit 118 leaving sufficient space outside the conduit topermit passage of hydraulic fluid to pistons 113. Surrounding the upperportion of rod 128 is corrugated liner tube 11. The upper end of theliner tube rests against head 111 while the bottom of the tube issupported by solid expanding cone 13. In the bottom of cone is anannular groove which receives the upper ends of sleeve 36 and springarms 38. The bottom of sleeve 36 is supported by cap 127 of hydrauliccylinder 128. On the bottom of polished rod 128 a piston 131 is mounted.This piston includes a flange member 132 and resilient cups 133. Abovethe resilient cups, passages 134i connect the interior of the hollowpolished rod to the space above the piston in cylinder 128. Below theresilient cups, hydraulic liquid reaches the interior of the hollowpolished rod through a tube 135 from pump 136. Pump 136 is driven byreversible motor 137 which receives electric power through leads 119.The pump takes liquid through intake tube 138 from the space below thepiston in cylinder 128. Below the motor and pump in cylinder 128 afloating piston 140 with an O-ring seal 141 is provided. The bottom ofthe cylinder is closed by plug 142 except for an opening 143 through theplug.

In operation the apparatus is assembled at the top of a well and afiberglass mat is wrapped around the corrugated liner and saturated withresin as descirbed in more detail in connection with FIGURE 1. Theassembly is then lowered into the well on the electric cable to thelevel at which the liner is to be set. The motor is then actuated tocause the pump to force liquid from the space below piston 131 into thespace above this piston. Floating piston 140 compensates for differencesin the volumes of the polished rod in cylinder 128 above piston 131 asthis piston moves in the cylinder, or more accurately, as the cylindermoves upwardly with respect to the stationary piston. As the pressureincreases, solid cone 13 and spring arms 38 are forced into corrugatedliner 11 to expand the liner.

As soon as cone 13 strikes the bottom of head 111, the pressure in thehydraulic system rises sharply. This increases the load on the motor.The increased load is indicated by an increased flow of current. Thisserves as a signal at the surface that the electric power to the motorshould be interrupted. Preferably, the increased current simply actuatesan overload switch to break the circuit automatically. The rotation ofthe motor is then reversed. At the same time, a mild pull is placed oncable 110. When the motor is reversed, the pump also reverses, releasingthe pressure within hollow rod 120 and permitting piston 131 to moveupwardly with respect to cylinder 128. This also means that rod 120 andhead 111 are moved upwardly with respect to the partially expanded liner11 and expanding cone 13. Head 111 is moved upwardly a-distancesuflicient to permit spring arms 38 to pass the upper edge of liner 11before cone 13 again contacts head 111. The direction of rotation of themotor is then again reversed applying pressure to the interior of rod120. The result is that slips 112 are set against the casing to hold theupper portion of the apparatus while the action of the hydraulicpressure in cylinder 128 forces the expanding head on up through theliner to complete the expansion of the liner. As soon as the enlargedportions on spring arms 38 pass the top edge of the liner, the apparatusis free to be removed from the well by lifting on cable 110.

FIGURES 9 and 10 represent the top and bottom portions, respectively, ofanother form of electric motor operated apparatus. In FIGURE 9 electriccable 1111 supports apparatus which is actuated by electric motorsthrough reduction gears and jack screws. In this case motor 151 actsthrough gear reduction 152 such as a planetary gear to turn jack screws153. This draws base 154 upwardly forcing sleeve 36, expanding cone 13,and spring arms 38 through corrugated tube 11 as previously described.When cone 13 comes in contact with guide 155,

the motor stalls and is automatically shut off as explained inconnection with FIGURES 7 and 8. The motor is then reversed whilelifting on cable 110 until guide 155 has been lifted a foot or so abovecone 13 so that spring arms 38 can be forced on through the liner. Motor156 is then operated to actuate reduction gear 157 and turn jack screw158. This draws slips cone 159 down, forcing slips segments 160 outagainst the casing. Keys 161 acting in slots 162 prevent the slipssegments from turning with respect to the housing of reduction gear 157,while keys 163 operating in slots 164 in turn prevent rotation of cone159 with the jack screw. When the slips are firmly set, the motorstalls, throwing an automatic overload switch in the circuit at the topof the well. Motor 151 is then actuated in the direction to pull cone 13and spring arms 38 through the remaining unexpanded portion ofcorrugated liner tube 11. The liner setting apparatus can then be liftedfrom the well by means of the electric cable 110. Thus, it is seen thatthe liner can be set by purely mechanical means independent of ahydraulic system.

In FIGURES l1 and 12 uninsulated wire line or steel cable 171 isattached to the top 172 of the liner setting apparatus by means of clamp173 and ring 174. Top 172 is screwed into the top of a long tube 175having ports 176 near the top. This tube is in turn attached to slipshousing 177. Slips 178 are of the hydraulically actuated type. The basesof slips 178 are exposed to annular space 179 between the housing andpolished rod 182. The upper part of slips housing 177 also serves as themounting base for a cup-type packer 183. The upper end of rod 184extends above the top of tube 175 and the bottom of the rod extendsthrough opening 185 in housing 177 and rests on break off relief seal186.

The bottom of slips housing 177 serves as the top of a hydrauliccylinder 187 which has an opening 198 through the wall near the top.Cylinder 187 carries piston 188. Polished rod 182 is hollow to a pointbelow piston 188 and openings 189 extend between the hollow interior ofthe rod and the space below piston 188 in cylinder 187. Polished rod 182continues on downwardly through bottom cap 190 of cylinder 187. Rod 182extends on through corrugated liner 11, expanding cone 13, sleeve 36,and spring arms 38 to base plate 191.

In operation the apparatus of FIGURES 11 and 12 is lowered into the wellon line 171 after a resin impregnated glass fiber mat is attached to theouter surface of liner tube 11. When the apparatus is at the desiredlevel in the well, hydraulic pressure is applied to the casing. This ispreferably done by introducing several gallons of liquid, for example amineral oil, into the well and then applying pressure to this oil bymeans of a compressed gas. The oil enters the top of packer 183 pressingthis packer against the casing wall. The oil also enters ports 176 intube 175 filling the interior of this tube. Oil passes down the hollowcenter of rod 182 and enters the portion of cylinder 187 below piston188. When pressure is applied to this oil by means of a compressed gasin the casing, a tight seal is formed between packer 183 and the casingwall. The pressure acts on the bases of slips 178 to set the slipsfirmly against the casing. Hydraulic pressure acting on the bottom ofpiston 188 pulls base plate 191 upwardly, forcing cone 13 and springarms 38 into liner 11 until cone 13 contacts cap 190. The pressure inthe casing is then released. This releases slips 178 and permits theupper portion of the apparatus to be lifted by line 171 a distancesufiicient to permit spring arms 38 to be pulled on through the linerbefore cone 13 again strikes cap 190. Reapplication of pressure to thecasing then resets slips 178 and pulls spring arms 38 the remainingdistance through the liner. As soon as spring arms 38 are clear of theliner, the casing pressure is released to release slips 178 and packer183 after which the apparatus is lifted from the well on line 171. Toprevent swabbing the casing with packer 183, a go-devil (not shown) canbe dropped to strike rod 184 which breaks seal 186 and allows the oil ontop of the packer to drain out below the packer, thus furtherfacilitating lifting of the apparatus from the well.

It will be apparent that it is possible to expand the corrugated linertube out against the casing by many means in addition to those shown inthe figures. Still other modifications will be apparent to those skilledin the art. For example, in the apparatus of FIGURES 11 and 12, thepressure which can be employed may be limited by the strength of easingweakened by corrosion. In this case the apparatus shown in FIGURE 13 maybe used. In this apparatus piston 188 and cylinder 187 below slipshousing 177 is the same as in FIGURE 12. Between this assembly andbottom cap 190, however, an intermediate connector 193 is provided inthe apparatus of FIGURE 13. Below this connector is a second cylinder194 with a port 195. Piston 196 operates in cylinder 194. Ports 197connect the interior of hollow rod 182 with the space below piston 196in cylinder 194. Thus, when pressure is applied to the liquid inside thehollow polished rod, this pressure acts on the lower surfaces of bothpistons 188 and 196, providing the same lifting force as in theapparatus of FIGURES 11 and 12 with only one-half the pressure in thecasing. This same modification can be used in the apparatus of FIGURES 1and 2, 7 and 8, or in any other system employing hydraulic pressure toactuate a piston. In the apparatus of FIGURE 7, for example, a secondcylinder and piston arrangement can be provided above piston 131 andcylinder 128, the opening to the hollow interior of the rod being placedabove the piston and the port being placed through the wall of thesecond cylinder below the piston near the bottom of the cylinder.

Still other modifications or combinations of the various types ofapparatus may also be desirable. For example, it is sometimes founddesirable to use a hydraulic slips mechanism as shown in FIGURES 7 and11 with the apparatus shown in FIGURES 1 and 2. Such hydraulic slips arealso shown on page 5232 of the 1960-61 edition of the Composite Catalogof Oil Field Equipment and Services. The advantage of such anarrangement in the apparatus of FIGURE 1 is that a short piston andcylinder can be used with a long corrugated liner section. After eachshort piston stroke, the pressure is released and the tubing is raised.The hydraulic slips are set and another piston stroke is then achievedby applying pressure again to the tubing. The tubing can, of course, beheld at the top of the well, but this allows considerable stretch in thetubing in a deep well. Sometimes it is also desirable not to place toomuch load on well tubing, particularly if the tubing has seenconsiderable use.

Still other apparatus will occur to those skilled in the art forperforming the specific step of reforming the corrugated liner tube intosubstantially cylindrical shape against the inner surface of the casing.The principal requirement is simply to expand the corrugated liner tubeout against the inner surface of the casing, reform it intosubstantially cylindrical form, and leave it in a state of substantiallymaximum compression. Although a few comments regarding this action wereincluded in the description of the operation of the apparatus shown inFIG- URE 1, a more complete explanation of the principles involved isprobably advisable.

The action depends upon the design of the corrugated liner tube. In itscorrugated form the maximum crosssectional dimension must be less thanthe internal diameter of the casing so the liner can be run into thecasing. After reforming into cylindrical form within the casing, theliner is to be left in substantially maximum compressive hoop stress.This means that the external crosssectional periphery of the corrugatedtube must be larger than the internal cross-sectional circumference ofthe casing so the final forming operation will place the liner incompression. The expression expanding the liner into contact with thecasing may be misleading. The expanding cone does expand the liner inthe sense that it forces the outer ridges of the corrugations outwardlyuntil they come in contact with the casing. Then the inner corrugationsare, in a sense, expanded radially outward toward the casing. It will beapparent, however, that the only way the inner ridges of the corrugatedliner can move outwardly, if the outer ridges have contacted the casing,is by compressing the wall of the liner. When the inner ridges of thecorrugations are still a considerable distance from the casing, a ratherlarge radial force may be required to compress the liner wall and causeradial movement outwardly toward the casing wall. After the linerreaches the position shown in FIGURE 4, however, a small radial pressurenear the middle of the remaining arch causes a very large force in adirection circumferentially around the liner. The reasons are the sameas those which cause a large force along the walls of any fiat arch whena small load is placed on the top of the arch. As a result, once theexpanding cone has formed the liner into the shape shown in FIGURE 4,the spring arms 38 in FIGURE 1, or the hydraulically driven arms 81 inFIGURE 6, need to exert only a small radial force to complete theforming of the liner into a substantially cylindrical shape inside thecasing.

Equipment such as that shown in FIGURE 1 was designed principally to seta liner in /2-inch casing of 15 /2- pound weight. This equipment wasalso used successfully to set liners in 15 and 17-pound casing of 5/2-inch size. A few data on use of the design in the 5 /2-inch, 15/2-pound casing are of interest. In all these cases, the liner wasformed from 5-inch diameter seamless mild steel tubing with a wallthickness of inch. This tubing was vertically, that is, longitudinallycorrugated by drawing it through a die to form eight corrugations havingan average bending radius of about inch. The maximum cross-sectionaldiameter of the corrugated tube was about 4 /2 inches. In forming thecorrugations, the metal was stretched at the outer ridges and compressedat the inner valleys to produce an external cross-sectional perimeterabout 2 percent longer than the original external circumference of thetubing.

The glass cloth was what is known as woven roving and was saturated withepoxy resin containing a polyamide catalyst to make the resin set afterthe liner was expanded in the casing. In the final lined casing, thelayer of glass fibers and plastic was found to average about 0.025 inchin thickness. The collet head was divided into eight spring arms, alittle less than 2 inches wide. The radial forces of the spring armsandthe forces required to pull the expanding cone and collet headthrough the corrugated tube are shown in Table 1.

The radial spring forces were determined by measuring the insidediameter of the liner set in each weight of pipe and then reading offthe appropriate force figure on the calibration curve of the spring. Ifthe liner had been reformed into a completely cylindrical form in the14- pound casing, the internal diameter of the liner would have beengreater than the completely expanded diameter of the collet spring arms.Actually, the liner was not completely reformed into a cylindrical shapein the 14-pound casing so the spring arm force approached but did notreach 0 pounds.

In the case of the force required to pull the expanding cone and colletspring head through the liner in the various weights of easing, thesewere separately determined and then simply added to obtain the totalfigure. The actual total force necessary to pull both the expanding coneand collet spring head through the liner simultaneously was generallysomewhat higher than the figure shown in Table 1. In the case of oneliner set in a 17- pound casing, for example, the interior surface ofthe liner was not Well lubricated so the expanding cone and collet headmoved through the liner in jumps. The total force in this case sometimesapproached 60,000 pounds. This total force was determined by multiplyingthe hydraulic pressure in the cylinder by ten since the area of thehydraulic piston was square inches. Since tensile forces of 75,000pounds are sometimes imposed on twoinch well tubing in other welloperations, it will be ap parent that this tubing could be used to pullthe expanding cone and collet spring head through the liner used in thiswork in a 17-pound 5 /2-inch casing even with a poorly lubricated liner.It will also be apparent, however, that if the liner is to be expandedin 20-pound, 5 /2- inch casing, some changes should be made. Forexample, a weaker spring may be used in the collet head, a liner eitherslightly smaller in circumference or slightly thinner may be employed, abetter lubricant may be applied to the inside of the liner, or astronger conduit such as 3-inch tubing, or drill pipe may be used.

It will be apparent that some limitations should be observed. Theprincipal limitations concern the corrugated liner tube and the casingin which it is to be set. A brief comparison of the circumference of theliner, after being set in the casing, to the perimeter of the corrugatedliner before setting, shows clearly that the yield strength of theliners was exceeded so that in most of the reforming operation the linermaterial was in plastic flow. This means that after the liner wasreformed into a cylindrical shape inside the casing, the liner was inmaximum compressive stress. The casing must be, of course, in suificienttensile stress to hold the liner in maximum compressive stress. It willbe obvious then that if the liner and easing are of the same metal, theliner must be thinner than the casing or the maximum tensile strength ofthe casing will be exceeded and it will burst.

Actually, the casing should be considerably thicker than the liner. Thisis because after the collet head arms have reformed the liner intosubstantially cylindrical shape, these arms continue to exert the radialforce shown in Table 1. Thus, the casing must withstand not only thestress imposed by the liner, but also the stress imposed by the springarms of the collet head. Ordinarily, the stress resulting from thespring arms is much less than that resulting from the liner. Theprincipal reason is that the force of the collet spring is applied toonly a very short section of easing, so the casing on each side of thecollet head helps to oppose this force. In order to have some margin ofsafety, however, it is generally advisable to use a steel liner which isnot more than about onehalf as thick as the steel casing in which it isset.

Of course, there are many types of steel used in wells and the liner canbe made either of steel or of several other type of metals or alloys,such as aluminum, aluminum alloys, brass, or the like, to meet specialrequirements, such as corrosion resistance. The more general limitationcan be stated, therefore, that the maximum compressive strength of thematerial of which the liner is made times the wall thickness of theliner must be less than the maximum tensile strength of the material ofwhich the casing is made times the wall thickness of the casing. Thislimitation includes the extreme case where the stress imposed by thecollet head arms is so small that it can be ignored. Generally, a linerwall thickness of only about one-half the indicated value should be usedto allow for a margin of safety. a

The liner should be annealed after forming into the corrugated shape inorder to reconvert the metal into a more malleable form. Otherwise, thework hardening which results from the corrugating operation may causethe liner to crack when reformed into cylindrical shape. If steel isused as a liner material, the radius of bending at the corrugations,ridges and valleys should be at least about three times the thickness ofthe metal to avoid cracking the steel when the corrugations are made.Preferably, the bending radius should be such that the corrugations areformed of arcs of circles.

The number of corrugations is controlled principally by the limitationon bending radius. Thus, if the liner wall thickness is /8 inch, thebending radius is about three times the thickness and the depth ofcorrugations is about six times the thickness, the distance betweenridges of the corrugations will be about 1 /2 inches. A distance ofabout 2 inches is preferred for this liner thickness in order to avoidthe danger of cracking the liner during the corrugating and settingoperation. Using this approximate 2 inch spacing between corrugations,the numbers of corrugations for liners of 3, 4 /2 and 6 inches inmaximum cross-sectional dimension are 5, 7, and 9, respectively. It isgenerally simpler to use even numbers of corrugations and collet headspring so the numbers should preferably be 6, 8, and '10 for the 3, 4 /2and 6-inch liners. These dimensions were selected since they areapproximately correct for the 4, /2 and 7-inch casing respectively.

In order to leave the liner in maximum compressive stress within thecasing, it is necessary that the external cross-sectional perimeter ofthe liner be greater than the internal circumference of the casing. Theamount by which the liner \vall must be compressed to insure that theliner tube reaches maximum compression is usually less than about A of 1percent. When a liner of glass fibers and plastic is provided betweenthe liner and the casing, and if the perimeter of the corrugated lineris any greater than the internal circumference of the casing, thisrequirement is satisfied. The upper limit on amount by which thecorrugated liner perimeter exceeds the internal circumference of thecasing is controlled principally by the force required to drive theexpanding cone and collet head through the liner. If the corrugatedliner perimeter is more than about 10 percent greater than the internalcasing circumference, the work required to reform the liner intocylindrical shape inside the casing will be great. The force required tomove the expanding heads through the liner at a desirable rate will becorrespondingly great. Therefore, the corrugated liner externalperimeter should ordinarily not exceed the casing internal circumferenceby more than about 10 percent. In the case of the liner set in the17-pound, 5 /2-inch casing in Table 1, the perimeter of the liner wasabout 4 percent greater than the internal circumference of the casing,

While the ridges and valleys of the corrugations are preferably parallelto the axis of the liner tube, it will be apparent that a tube in whichthe corrugations spiral around the tube to some degree may also be used.Preferably, however, the tube should be substantially longitudinallycorrugated. That is, a ridge of the corrugations should not vary morethan about an inch or two from a line parallel to the axis of the tubein a foot-long section of the tube.

The radial force exerted by the spring arm of the collet head should liewithin certain limits. As shown in Table 1, however, satisfactoryresults can be obtained when these limits are rather wide. The forceshould be at least about 1,000 pounds for an arm about 2 inches wide inorder to insure a good reforming action on the corrugated liner.Preferably, the force should not be greatly in excess of about 5,000pounds, principally to decrease the drag of the arms as they are forcedthrough the liner. As previously noted, there are several ways to overome this problem so even greater radial forces are ofter permissible.Ordinarily, however, they are not required. The same range of radialforces applies, of course, to the hydraulically-driven arms shown inFIGURE 6. In general, the radial force may be said to be sufficientlygreat to expand the corrugated tube into substantially cylindrical shapewithout imposing a tensile stress in the casing in excess of the maximumtensile strength of the material of which the casing is made.

The glass fibers which are applied outside the liner and are saturatedwith liquid resin can be of several types. In selecting an appropriatetype, the principal functions of the glass fibers should be borne inmind. The main function is to carry sufficient resin to fillirregularities between the casing and liner and to fill holes throughthe casing, forming a button outside of the casing wherever possible.External pressure applied to such a button forms a pressure-actuatedseal. The glass fibers must also form barriers to prevent excessive fiowof the resin from between the liner and easing until the resin has setto a hardened state. To do this, the glass fibers must withstand thefull radial pressure applied by the line against the casing. It mustwithstand this pressure permanently, with the aid of the hardened resin,since it is the existence of this pressure which prevents leakagebetween the liner and the casing.

The glass fibers best adapted to these purposes are obtained in the formof cloth, Woven of threads which are, in turn, spun from very fine glassfibers, preferably less than 0.001 inch in diameter. Mats in Which thethreads are stuck together with an adhesive or plastic may also be used.The glass mats may be simply wrapped around the outside of thecorrugated liner and held in place by bands, threads, or wires.Preferably, the glass mat is glued to the corrugated surface of theliner. In this case, the resin may be applied with a blade or wire brushafter the glass mat is glued to the liner surface. If the mat is simplywrapped around the liner, the resin is most conveniently applied to theglass mat, again with a blade or wire brush, before the mat is wrappedaround the liner. In any case, the glass mat should be thoroughlysaturated with the resin.

Any resin which will cure or set hard, either naturally or artificially,in the well may be employed. Typically, these resins are thermosettingresins, 'i.e., resins which are capable of undergoing a permanentphysical change under the influence of well temperature or anartificially induced higher temperature. Polyester or epoxy resins areexamples. Other suitable resins include urea, resorcinol, and phenolformaldehydes, and the like. Epon 828, an epoxy resin manufactured byShell Chemical Company, is an example of a preferred epoxy resin. As iswell known in this art, these resins may be combined and variouscatalysts or curing agents employed in various concentrations so thatthe setting or curing time or pot life for various well depths orvarious temperatures may be controlled. Versamid resin 140, a polyamidemanufactured by General Mills, Inc., is an example of a preferredcatalyst which, in the ratio of about 30 parts by volume to 70 parts ofthe Epon 828 epoxy resin, has a pot life at room temperature of about 3to 3 /2 hours. Such resins when set, i.e., when they are curedsufiiciently to be self-supporting and relatively rigid, are referred toherein as plastics.

As previously noted, a. lubricant should be applied to the insidesurface of the corrugated liner tube to decrease frictional drag on theexpanding cone and collet head. Use of such a lubricant is notessential, but is recommended. The lubricant may be mineral oil,vegetable oil such as cottonseed oil, or animal oil such as sperm oil.It may also be in a more solid form, such as parafiin wax, bees-wax,tallow, or the like. A preferred lubricant is made up of about percentozokerite, or its purified form ceresin wax, and about 10 percent offinely divided particles of malleable material, such as copper, lead,graphite, nutshells, or the like.

The principal application of the apparatus is to patching holes incasing in wells. These may take the form of small holes, large holes,parted casing, splits, or the like. The apparatus is also applicable tocasing which has no holes. Thus, the patch may be applied to a badlycorroded section of casing before any actual holes appear. It may alsobe applied inside relatively uncorroded casing to strengthen the casingagainst external pressure, for example. In a broad sense, a well casingis one embodiment of a pressure vessel. Thus, the patch should beconsidered applicable to other vessels, particularly those subjected toexternal pressure such as underwater storage tanks, or the like. Stillother applications will occur to those skilled in the art.

When a patch is set in casing, it frequently extends across a weak,perforated or split section of casing and the ends are set inside ofbetter sections of the casing. It is in these end sections of casingthat the principal seal is generally made. Therefore, the limits statedabove a to the strength and thickness of the casing are intended to l3apply to the stronger portions in which the ends of the patch are setrather than the weak or split portion opposite the center of the patch.

When a patch is to be set across the gap in parted casing, for example,the coating of glass fibers and resin can, at least theoretically, beomitted from the center section opposite the gap in the casing.Actually, however, it is usually important to have the coating of glassfibers and resin extend over the entire length of the corrugated tube.The principal reason is to provide corrosion resistance. Theresin-saturated glass fiber mat protects the liner from corrosive fluidsoutside the casing. In addition, in setting a patch in a deep well, itis difficult to place it exactly where desired. Therefore, at least aportion of an uncoated section of the liner might be placed opposite thecasing itself rather than opposite the gap in the casing. It has alsobeen noted that the resin tends to form a fillet against the ends of theparted casing. This fillet usually form-s a pressure-actuated sealagainst the casing ends and aids in preventing entrance of fluidsbetween the casing and liner. For all these reasons it is consideredimportant that the coating of glass fibers and resin extend over theentire outside surface of the corrugated tube.

In the embodiment of my invention in which the liner is sealed in thebottom of a casing string and extends into the previously unlinedportion of the well, the glass fibers and resin should also be usedaround the portion of the liner opposite the open hole. The principalreason is to form a good seal between the liner and the formation. Inorder that the same diameter of liner can be used opposite both thecasing and the open hole, the well below the casing should be drilled orreamed to a diameter within a quarter of an inch or so of the internaldiameter of the casing. In a new well this is no problem. In an old wellit is customary to clean out the bottom of a well before setting aliner. During this operation a bit or reamer should be run to insure anopen hole diameter below the casing nearly as large as the internalcasing diameter. The liner can then be set in the open hole as well asin the bottom of the casing by the same method as if the entire linerwas being set in casing.

In order to leave as small a section of unlined well as possible at thebottom of the Well, the hydraulic cylinder may be placed above the linerrather than below it. Such a design is shown, for example, in mycopending US. patent application Serial Number 179,609, filed March 14,1962. This same copending application also shows by way of example adesign for a different type of expanding head which can be used ifdesired. The corrugated tube can also be expanded by simply mounting theexpanding head on the bottom of drill pipe and forcing it downwardlythrough the liner. Thi operation is possible with a bottom hole linersince the bottom of the Well supports the liner. The operation is alsodescribed in more detail in my copending US. application 179,609.

In some cases it may be desirable to hang a liner such as a perforatedliner or sand screen below the casing, no seal to the formation beingrequired. In this case it is necessary to corrugate and subsequentlyexpand only the top portion of the liner into contact with the casing.In this case the expanding head shown in FIGURE 1 is mounted in theportion of the unexpanded liner below the corrugated section, therestraining extensions on the top of the spring arm permitting thisoperation to be performed easily. The corrugated tube with theuncorrugated portion below it is then lowered into the well and expandedinto contact with the lower portion of the casing exactly as if theuncorrugated portion was not attached. It is also possible to force anexpanding head downwardly through the corrugated portion as explainedabove, the expanding head being forced only through the corrugatedportion, however. Still other specific techniques and applications willbe apparent to those skilled in the art.

In the foregoing description, many specific materials are mentioned. Forexample, glass'fibers or glass fabric is suggested. It will be apparentthat other materials which are physically equivalent to those namedshould be considered to be within the scope of my invention. Forexample, some types of strong rock wool fibers should be considered theequivalents of glass fibers if their physical properties aresubstantially the same as those of glass fibers.

I claim:

1. Apparatus for placing a metallic liner in a substantially cylindricalmetallic vessel comprising a longitudinally corrugated tube of malleablemetal, said tube having an external cross-sectional perimeter greaterthan the internal cross-sectional circumference of said vessel, and thethickness of the wall of said tube times the maximum compressivestrength of the metal of which said tube is made being less than thethickness of the wall of said vessel times the maximum tensile strengthof the metal of which said vessel is made, a glass fiber mat surroundingsaid tube, said mat being saturated with a liquidresin capable of beingset to a hardened state, and means for expanding said tube to asubstantially cylindrical form within said vessel without imposing atensile stress in the wall of said vessel in excess of the maximumtensile strength, said means for expanding said tube including means forrestraining longitudinal movement of said tube, an expanding assemblyhaving a first tube-expanding head and a second tube-expanding head,said first tube-expanding head having a generally conical solid surfacewith a maximum diameter sufiicient only partially to expand said tube assaid expanding assembly is forced through said tube, and said secondtube-expanding head having a set of tube-expanding elements capable ofbeing forced radially outwardly of the first head in a directionsubstantially perpendicular to the axis of said tube, said elementsbeing capable of moving inwardly toward the axis of said tube uponapplication of excessive force to said elements during the expansion ofsaid tube, means for forcing said tubeexpanding elements outwardly andmeans for forcing said expanding assembly through said tube.

2. The apparatus of claim 1 in which said tube-expanding elements areenlarged ends on the spring arms of a spring collet and means forforcing said elements outwardly consists of the spring arms and thecollar to which these spring arms are attached.

3. Apparatus for placing a metallic liner inside steel casing in a wellcomprising a longitudinally corrugated tube of malleable steel, theexternal cross-sectional perim eter of said tube being greater than theinternal circumference of said casing, and the wall thickness of saidtube being less than the wall thickness of said casing, a hollow conduitfor lowering said tube into said well, said tube being mounted on saidconduit, a glass fiber mat surrounding said tube, said mat beingsaturated with a liquid resin capable of being set to a hardened state,and means for expanding said tube to a substantially cylindrical formwithin said casing without imposing a tensile stress in the wall of saidcasing in excess of the maximum tensile strength, said means forexpanding said tube including means for restraining longitudinalmovement of said tube, an expanding assembly having a firsttube-expanding head and a second tube-expanding head, said firsttube-expanding head having a generally conical solid surface with amaximum diameter sufficient only partially to expand said tube as saidexpanding assembly is forced through said tube, and said secondtube-expanding head having a set of tube-expanding elements capable ofbeing forced radially outwardly of the first head in a directionsubstantially perpendicular to the axis of said tube, said elementsbeing capable of moving inwardly toward the axis of said tube uponapplication of excessive force to said elements during the expansion ofsaid tube, means for forcing said tubeexpanding elements outwardly andmeans for forcing said expanding assembly through said tube.

4. The apparatus of claim 3 in which said means for forcing saidexpanding assembly through said tube is a hydraulic piston actuated bypressure applied through said conduit.

5. The apparatus of claim 3 in which said tube-expanding elements areenlarged ends on the spring arms of a spring collet and the means forforcing said elements outwardly consists of the spring arms and thecollar to which these spring arms are attached.

6. Apparatus suitable for expanding a corrugated liner tube in asubstantially cylindrical metallic vessel comprising means forrestraining longitudinal movement of said tube, an expanding assemblyhaving a first tube-expanding head and a second tube-expanding head,said first tubeexpanding head having a generally conical solid surfacewith a maximum diameter sufficient only partially to expand said tube assaid expanding assembly is forced through said tube, and said secondtube-expanding head having a set of tube-expanding elements capable ofbeing forced radially outwardly of the first head in a directionsubstantially perpendicular to the axis of said tube, said elementsbeing capable of moving inwardly toward the axis of said tube uponapplication of excessive force to said elements during the expansion ofsaid tube, means for forcing said tube-expanding elements outwardly andmeans for forcing said expanding assembly through said tube.

7. The apparatus of claim 6 in which said tube-expanding elements areenlarged ends on the spring arms of a spring collet and the means forforcing said elements outwardly consists of the spring arms and thecollar to which these spring arms are attached.

8. Apparatus suitable for expanding a corrugated liner tube in a wellcomprising means for lowering said liner tube to the desired depth insaid well, means for restraining longitudinal movement of said tube, anexpanding assembly having a first tube-expanding head and a secondtube-expanding head, said first tube-expanding head having a generallyconical solid surface with a maximum diameter sufiicient only partiallyto expand said tube as said expanding assembly is forced through saidtube, and said second tube-expanding head having a set of tubeexpandingelements capable of being forced radially outwardly of the first head ina direction substantially perpendicular to the axis of said tube, saidelements being capable of moving inwardly toward the axis of said tubeupon application of excessive force to said elements during theexpansion of said tube, means for forcing said tube-expanding elementsoutwardly and means for forcing said expanding assembly through saidtube.

9. The apparatus of claim 8 in which said tube-expanding elements areenlarged ends on the spring arms of a spring collet and the means forforcing said elements outwardly consists of the spring arms and thecollar to which these spring arms are attached.

References Cited by the Examiner UNITED STATES PATENTS 958,517 5/10Mettler 166217 1,981,525 11/34 Price 16649 2,377,249 5/45 Lawrence166-212 X 2,583,316 1/52 Bannister 166207 X 2,901,044 8/59 Arnold166-212 X 3,028,915 4/62 Jennings 166-46 BENJAMIN HERSH, PrimaryExaminer.

1. APPARATUS FOR PLACING A METALLIC LINEAR IN A SUBSTANTIALLYCYLINDRICAL METALLIC VESSEL COMPRISING A LONGITUDINALLY CORRUGATED TUBEOF MALLEABLE METAL, SAID TUBE HAVING AN EXTERNAL CROSS-SECTIONALPERIMETER GREATER THAN THE INTERNAL CROSS-SECTIONAL CIRCUMFERENCE OFSAID VESSEL, AND THE THICKNESS OF THE WALL OF SAID TUBE TIMES THEMAXIMUM COMPRESSIVE STRENGTH OF THE METAL OF WHICH SAID TUBE IS MADEBEING LESS THAN THE THICKNESS OF THE WALL OF SAID VESSEL TIMES THEMAXIMUM TENSILE STRENGTH OF THE METAL OF WHICH SAID VESSEL IS MADE, AGLASS FIBER MAT SURROUNDING SAID TUBEM SAID MAT BEING SATURATED WITH ALIQUID RESIN CAPABLE OF BEING SET TO A HARDENED STATE, AND MEANS FOREXPANDING SAID TUBE TO A SUBSTANTIALLY CYLINDRICAL FORM WITHIN SAIDVESSEL WITHOUT IMPOSING A TENSILE STRESS IN THE WALL OF SAID VESSEL INEXCESS OF THE MAXIMUM TENSILE STRENGTH, SAID MEANS FOR EXPANDING SAIDTUBE INCLUDING MEANS FOR RESTRAINING LONGITUDINAL MOVEMEN OF SAID TUBE,AN EXPANDING ASSEMBLY HAVING A FIRST TUBE-EXPANDING HEAD AND A SECONDTUBE-EXPANDING HEAD, SAID FIRST TUBE-EXPANDING HEAD HAVING A GENERALLYCONICAL SOLID SURFACE WITH A MAXIMUM DIAMETER SUFFICIENT ONLY PARTIALLYTO EXPAND SAID TUBE AS SAID EXPANDING ASSEMBLY IS FORCED THROUGH SAIDTUBE, AND SAID SECOND TUBE-EXPANDING HEAD HAVING A SET OF TUBE-EXPANDINGELEMENTS CAPABLE OF BEING FORCED RADIALLY OUTWARDLY OF THE FIRST HEAD INA DIRECTION SUBSTANTIALLY PERPENDICULAR TO THE AXIS OF SAID TUBE, SAIDELEMENTS BEING CAPABLE OF MOVING INWARDLY TOWARD THE AXIS OF SAID TUBEUPON APPLICATION OF EXCESSIVE FORCE TO SAID ELEMENTS DURING THEEXPANSION OF SAID TUBE, MEANS FOR FORCING SAID TUBEEXPANDING ELEMENTSOUTWARDLY AND MEANS FOR FORCING SAID EXPANDING ASSEMBLY THROUGH SAIDTUBE.